Different measures, different outcomes? Survey into the effectiveness of chronic pain clinics in a London tertiary referral center

BACKGROUND Chronic pain clinics aim to improve challenging conditions, and although numerous studies have evaluated specific aspects of therapies and outcomes in this context, data concerning service impact on outcome measures in a general pain population are sparse. In addition, current trends in commissioning increasingly warrant services to provide evidence for their effectiveness. While a plethora of outcome measures, such as pain-intensity or improvement scores, exist for this purpose, it remains surprisingly unclear which one to use. It also remains uncertain what variables predict treatment success. OBJECTIVES This cross-sectional study was conducted to evaluate clinic performance employing different tools (pain scores, pain categories, responder analysis, subjective improvement, satisfaction), and to determine predictors of outcome measures. PATIENTS AND METHODS Patients attending scheduled clinic follow-up appointments were approached. They were asked to complete the modified short-form Brief Pain Inventory (BPI-SF) that also included assessments for satisfaction and subjective improvement. Comparisons were made with BPI-SF responses that were completed by each patient on admission. Nonparametric tests were employed to evaluate service impact and to determine predictors for outcome. RESULTS Data of 118 patients were analyzed. There was considerable variation in impact of pain clinics depending on the outcome measure employed. While median pain scores did not differ between admission and follow-up, scores improved individually in 30% of cases, such that more patients had mild pain on follow-up than on admission (relative risk 2.7). Furthermore, while only 41% reported at least moderate subjective improvement after admission to the service, the majority (83%) were satisfied with the service. Positive treatment responses were predicted by "number of painful regions" and "changes in mood", whereas subjective improvement was predicted by "helpfulness of treatments". CONCLUSION Depending on the outcome measure employed, pain clinics showed varying degrees of impact on patients' pain experiences. This calls into question the current practice of using nonstandardized outcome reporting for evaluation of service performances.